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Vesicular transport. Dr. med. habil. Kőhidai László Assoc. Professor Depertment of Genetics, Cell- and Immunoibiology Semmelwesi University 2008. Intracellul ar ve s i cular tra nsport. Communication – intracellular; - cell-environment Membrane system
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Vesicular transport Dr. med. habil. Kőhidai László Assoc. Professor Depertment of Genetics, Cell- and Immunoibiology Semmelwesi University 2008.
Intracellular vesicular transport Communication – intracellular; - cell-environment • Membrane system • Uptake of substances and transport to the place of digestion (lysosomes) - endocytosis • Transport of proteins between ER-Golgi and to the surface membrane - exocitózis
Intracellular vesicular transport • Bidirectional, transport between compartment is balanced • Continous recyclicling of membrane proteins
Pathway of biosynthetic- and secretory processes Endocytosis Recycling
Transport vesicles • Membrane bounded vesicles filled with different cargos • Secretion • Lysosomal enzymes • Components of surface membrane and the ECM • Direction of transport is determined by the components of the membrane see: donor and target compartments
Molecular bases of vesicular transport • Biosynthetic-secretory and endocytotic pathways join 10 or more compartments • Direction of the transport and fusion are determined by molecular matching (receptor/ligand)
Coated vesicles Role of the coat: • Components of the membrane (e.g. receptors) are concentrated into patches • Removal of coated surfaces and formation of vesicles
Types of coated vesicles • Clathrin-coated vesicles • COPI-coated vesicles • COPII-coated vesicles Each type of vesicle has its own transport
We can distinguish the TEM morphology of the three types of vesicles
Clathrin-coated vesicle: Golgi – surface mamembrane transport COPI- and COPII-coated vesicles: rER - Golgi transports
The building block of the clathrin-coat: The triskelion
Clathrin-coat Triskelion zikk-zakk and globular structural elements
Comparison of clathrin composition Light chain Heavy chain
Protein-protein and protein-lipid associations under clathrin coat
Releasing of clathrin-coated vesicles Alberts et all. Molecular Biology of the cell
Receptor-mediated endocytosis Role of dynamin in the process of vesicle release Dynamin is a G-protein, it binds and cleaves GTP Alberts et all. Molecular Biology of the cell
Receptor-mediated endocytosis Alberts et all. Molecular Biology of the cell
Fusion of vesicle and target membrane (2) NSF – N-ethylmaleimide sensitive factor SNAP – soluble NSF attachment protein SNAP-25 – synaptosomal associated protein 25 kDa VAMP – vesicle associated membrane protein
A significant component of the vesicle-membrane fusion: a protonpump a subunit –VPH1 d subunit VMA6 4c, c’ and c’’ subunit – VMA3, VMA11, VMA16
SNAP-25 VAMP Syntaxin n-Sec1 Syntaxin complex n-Sec1-syntaxin komplex Association of main components in membrane fusion SNAP-25 – synaptosomal associated protein 25 kDa VAMP – vesicle associated membrane protein
Vesicularis transport – „Budding”
Vesicularis transport – „Docking”
syntaxin VAMP SNAP-25 egyéb CCP – cl.-coated pit CCV – cl-coated vesic. DCV – dense core vesic. IC – intermed. comp. Subcellular distribution of SNARE proteins SNARE – soluble N-ethylmaleimide sensitive factor attachment protein receptor
Number of genes responsible for vesicular transport Phylogenetical approaches
Evolution of SNARE-s S. cerevisiae H. sapiens